Field of the Invention
The present invention relates to a piezoelectric material, and in particular, relates to a piezoelectric material that does not substantially contain lead. The present invention also relates to a piezoelectric element, a multilayered piezoelectric element, a liquid discharge head, a liquid discharge apparatus, an ultrasonic motor, an optical device, an oscillatory device, a dust removing device, an imaging apparatus, and an electronic device that use the piezoelectric material.
Description of the Related Art
Generally, a piezoelectric material is an ABO3-type perovskite metal oxide such as lead zirconium titanate (hereinafter referred to as “PZT”). PZT, however, contains lead as an A-site element, and therefore, the environmental impact of PZT is regarded as a problem. Thus, there is a need for a piezoelectric material using a perovskite metal oxide that does not contain lead.
As a piezoelectric material using a perovskite metal oxide that does not contain lead, barium titanate is known. Further, to improve the properties of the piezoelectric material, a material is developed based on the composition of barium titanate.
Japanese Patent No. 5344456 demonstrates that barium zirconate and barium calcium titanate have a morphotropic phase boundary, and with the composition of the morphotropic phase boundary, the piezoelectric properties improve near room temperature.
Further, Japanese Patent No. 5217997 demonstrates that an oxygen vacancy formed by adding Mn, Fe, or Cu to a material obtained by replacing a part of the A site of barium titanate with Ca pins a ferroelectric domain, and accordingly the mechanical quality factor improves near room temperature.
Both Japanese Patents No. 5344456 and No. 5217997, however, are techniques focused on the piezoelectric properties near room temperature. When a device is driven, properties of the piezoelectric constant and the mechanical quality factor both need to be excellent in a device driving temperature range (e.g., −30° C. to 50° C.).